Coffee consumers are being urged to "think before they drink" as a film accusing the industry of not giving producers a fair deal opens in the UK.

The documentary film Black Gold says farmers in the developing world are typically paid around 60p for 1lb of coffee, forcing them to remain poor.

National Coffee Day, which is supported by fair-trade coffee firms and campaigners, aims to raise awareness.

The big coffee multinationals deny they are exploiting coffee growers.

Black Gold, which is about Ethiopian coffee producers, won praise after being screened at film festivals last year.

It was made by Nick and Marc Francis, two brothers from Brighton, who wanted to show how some farmers lost out in global trading.

Marc said some farmers were "struggling to eat" and the film aimed to demonstrate that they needed to be paid a fair price for their produce.

The brothers said they hoped people would support the awareness day on Friday.

'Consumer lifestyle'

"We wanted to make a film which forced us as Western consumers to question some of our basic assumptions about our consumer lifestyle," they said in a statement.

The film claims that coffee growers typically receive less than half of what they need to afford schools and basic health care.

We buy to the market price and we have to do that because we are a business that operates in the market

Jonathan Horrell Kraft

Jonathan Horrell, director of corporate affairs at Kraft, which owns Kenco coffee, one of the biggest coffee roasters and importers in the UK told BBC Radio 4's Today programme that Black Gold was "an important and powerful film" that raised important issues.

He said main problems were that farmers did not always get the full market price and that the market price for coffee had been "volatile in recent years", dropping down to 45 cents for 1lb in 2001.

"We buy to the market price and we have to do that because we are a business that operates in the market," he said.

He added: "It's very important that farmers have access to the proper market price and also it's important for all parts of the coffee industry that there's some stability in the market that enables people to make a return."

Helen Ireland, from coffee brand Cafe Direct, said the film highlighted the "impacts of the unfair trading system" that were happening all over the world.

"You can create a trading and business model that has a fair system across the supply chain and gives that stability to farmers who are guaranteed a fair price."

She said Cafe Direct had taken this "one stage further" with growers who owned the company and who received investment and training.

"It's seen as a commodity, but at the end of the day there are people behind that coffee and we've shown, if you look at a different way of trading - and we trade directly with the growers - there is a way that benefits everyone and gets the quality to the consumer."